After connecting the Pi to a VPN-service following these steps, i am still able to reach the Pi from within my local network ("ssh 192.168.0.2"), however, from outside ("ssh my-router-address"), i cannot reach it anymore.

Maybe that's what a VPN should actually provide. Yet, since i want to control my Pi from outside via VNC (and benefit from that VPN connection), i'm a bit puzzled about how to make sure my Pi stays reachable from outside, even though it's connected to that VPN service.

In my understanding, as soon as the Pi connects to the VPN, it is assigned a dynamic IP automatically. So, while i think it could be possible to connect via this new IP, i kind of have no chance of even knowing it.